Crops and Methods for Soil Improvement

by Alva Agee

Sweet Clover.—Much interest has been aroused within recent years in sweet clover, a legume that formerly was regarded as a more or less pernicious weed. Its friends regard it as a promising forage crop, but too little is definitely known to permit its advocacy here except as a soil-builder in the case of poor land that is not too deficient in lime to permit good growth. Experiments have shown that a taste for this bitter plant can be acquired by livestock, and it is nearly as nutritious as alfalfa when cut before it becomes coarse and woody. It is a strong grower, sending its roots well down into the subsoil, and its great ability to secure nitrogen from the air enables it to make a very heavy growth of top. The yield in forage usually exceeds that of the clovers.

Its most peculiar characteristic is its ability to thrive in a poor, compact soil that contains little humus. It may be seen in thrifty condition on roadsides and in waste places that seemingly would not support other plants. Laying aside all consideration of its possibilities as a forage crop, it will come into greater popularity as a soil-builder on thin land. It is found usually on land of limestone formation, and shares with other legumes a liking for lime, but it has been grown successfully in regions that are known to have a lime deficiency.

There are two biennial varieties and one annual. The biennial having white blossoms is the one most commonly seen, but the smaller variety with yellow blossoms is more leafy and palatable. The larger variety is the better fertilizer.

The seed does not germinate readily, and 20 to 30 pounds is used per acre. The soil should be compact, and the seeding can be made in the spring with a cover crop, or in August by itself. Inoculation is necessary if the right bacteria are not present. Soil from an alfalfa field will serve for inoculation.

An effort should be made to grow sweet clover on all infertile hillsides that are lying bare. It stops washing and paves the way for a sod of nutritious grasses.

Rye as a Cover Crop.—As has been stated elsewhere, the plant that stores nitrogen in its organic matter is most desirable, but the greater part of the soil's stock of humus did not come through legumes. Among the good cover crops is rye, both on account of its ability to grow under adverse conditions and because it produces a large amount of material for the soil. When seeded in the early fall, its roots fill the soil the following spring, and the tops furnish all the material that can be plowed down with safety. In northern latitudes it is the most dependable of all winter cover crops, making some growth in poorly prepared seed-beds and on thin land. The most value is obtained from early seedings, thus securing a good fall growth. Two bushels of seed are sufficient in good ground seeded ten weeks before winter begins, but two or three pecks should be added to this amount if the rye can be given only a few weeks of growth before frost locks up the soil. Rye can grow in warm spells of winter, and starts early in the spring. It uses up some available fertility that might otherwise be lost, and releases it when it rots in the ground.

When to plow Down.—If rye has made a good growth before spring, the roots run deeper than the plow goes, and holds the soil much like a grass sod. In such a case the plowing may be made early in the spring without regard to the rye, though organic matter increases rapidly day by day if the rye is permitted to grow. As a rule, it is safest to plow down before the plants are eighteen inches high. They dry land out rapidly, and any mass of matter in the bottom of the furrow interferes with the rise of water from the subsoil. When the land is wanted for oats or corn, a jointer should be used on the plow to insure burying all the crop.

Buckwheat.—An excellent crop for green-manuring is buckwheat. It has such unusual ability to grow in a poor soil that the farmer who makes free use of it as a grain crop never boasts of acreage planted, assuming that his land will not be highly regarded if known to be devoted chiefly to buckwheat. It does not withstand heat well, especially from period of blossoming to maturity, and therefore is restricted to cool latitudes. When grown for grain, it usually is not planted until July, and matures a crop in a shorter period than any other grain. It is sensitive to frost, but may be planted as soon as the ground is warm, and will give a good body of matter for plowing down within eight weeks. The root growth is not extensive, but the crop leaves naturally heavy soils more mellow, and it is an excellent cleansing crop for weed-infested fields. It makes a less heavy growth than rye, but can be used at a time of the year that rye would fail. There is time in a single season to grow two crops of buckwheat for green-manuring, turning the first crop down when the blossoms appear.

Oats.—When a fall growth is wanted for the soil, and it is preferred that the plants be dead in the spring, oats make a good catch crop.

Thin land which is wanted for seeding to wheat and grass in the fall, or for timothy and clover seeding in August, may use oats as a spring cover crop. A large amount of humus-making material may be gained by this means. The only danger lies in the effect upon soil moisture. The oat crop uses up the water freely in its growth, and when permitted to form heads before being plowed down, the mass of material in the bottom of the furrow does not rot quickly enough to induce the rise of water from the subsoil. The land should be plowed early enough to permit a solid seed-bed to be made.